Food dehydrator



Sept. 26, 1944. H. J. BURNETT 7 2,359,199

FOOD DEHYDRATOR Filed Aug. 3, 1940 4 Sheets-Sheet 1 Ml WWW W as} ifINVENTOR.

.ATTORNEYs Sept. 26,.1944. H. J. BURNETT FOOD DEHYDRATQR Filed Aug. 5,1940 4 Sheets-Sheet 2 Sept. 26, 1944. 1-1. J. BURNETT ,1

FOOD DEHYDRATCJR Filed Aug. 3, 1940 4 Sheets-Sheet 4 A TTORNEYS.

Patentedv Sept. 26, 1944 UNITED STATES PATENT OFFICE Application August3,1940, Serial No. 350,482

8 Claims. This invention relates to an apparatus for dehydrating foodand has for one of its objects to provide an apparatus which will removea large portion of the moisture from a raw food. v

-Another object of the invention is to remove the moisture under suchconditions that there will belittle or no loss of the vitamin content ofthe raw food during such operation.

.Another object of the invention is to remove or dehydrate the raw foodquickly that oxidation will not occur.

'Another object of the invention is to provide an apparatus in which themanipulation of the food product will be mechanical and very littlemanual operations or handling will be necessary.

A more specific object of the invention is to enhance and speed up thedehydration of the food product by the preliminary treatment of the sameas to increase the circulation of air about the particles of theproduct.

, Another object of the invention is to provide a flow of .air in asutlicient amount so that there will never be a moisture saturation ofthe air, and efllcient and speedy dehydration will be con tinuallyperformed.

Another-object ofthe invention is to provide a turbulent condition ofthe air which is to flow about the raw food product in order that all ofthe air may comein contact with the food. Another objectof the inventionis to provide an aspirator eflect for the drawing of the air through theraw food product.

vation the hopper and a portion of the pick-up buckets and takenonsubstantially line 22 of Fig. 1;

Fig. 3 is a side elevation of a portion of the apparatus continuing thatfragmental portion shown at the right scale; I

Fig. 4 is a sectional view of a portion of the apparatus shown inelevation in Fig. 3 but on a larger scale;

Fig. 5 is a section on substantially line 5-5 of Fig. 4;

Fig. 6 is a diagrammatic view of two of the heating banks illustrated inFig. 4;

Fig. 7 is a side elevation of certain of the conveying apparatusillustrated in Fig. lbut on a larger scale;

Fig. 8 is a top plan view of a portion of the conveying apparatus shownin Figs. 1 and 7 tom sifter.

In the preparation of a dehydrated food product such as raw carrots, itis desirable that these carrots be dehydrated under conditions whereby'Anotherobject of the invention is to cause an even action of the airupon the food product by reason of the even distribution of the producton the conveying parts of the machine.

' Another object of the invention is to'provide an apparatus fordividing deposited quantities of the product to be treated and conveyingthe divided amounts for even distribution over the apparatus.

Another object of the invention is to so manipulate the parts of theapparatus to which thetheir high content of certain of the vitamins bemaintained, which is accomplished by dehydrating at controlledtemperatures relatively low and at a comparative rapid rate wherebyoxidation does not occur. In order to accomplish this result, severaldifferent steps must be mechanically provided for, which I have done ina flow line apparatus whereby the carrots, or for that matter, any otherfoo d product, are first washed, are preliminarily sliced, ground, andconveyed through an arrangement where even distribution may be had todeposit the stock upon a reticulated travelling conveyor, such as ascreen, which will cause the finely-divided food product to be dried ina plurality of different compartments that the drying action may beperformed quickly and efliciently and the material discharged at theother end of the flow line. The

washed an apparatus designated generally I5.

of Fig. l but on a smaller which is of the rotary barrel type cleaner inwhich water is operated by radial outward streams on the stock in thedrum I8 formed of slats being equipped in their inner surfaces withbrushes to clean off the dirt that may have accumulated on the rawstock. Suitable water is suppl ed through The drum is I conduit I Icontrolled as at I8. driven from the motor I9, drive belt 28 and surfacedrive pulleys 2I. After the stock has engaged the brushes and streams ofwater have the raw food, such as carrot, moves with the conveyor, itwill be cut by the-knives into slices which will be discharged ontotheconveyor belt 28. This slicer is operated from an'electric motor 29through belt 38 which also serves through belt 3| to drive the conveyor28.

The conveyor 28 consists of a belt with a plurality of slats 32 acrossthe same which will Pick up the slices of the carrot and carry them to agrinding device designated generally 35. This grinder has a hopper 36 toreceive'the sliced carrots, conveying them to a chute 31 in which thereis a worm to move them to the rotary grinder which pulverizes the carrotslices and discharges them into a.hopper 38. A grinder which has beenfound suitable for this purpose is the Mikro Pulverizer which isavailable onthe market. This grinding serves to pulverize the carrots intheir own juices in such a manner that the solid part of the carrotabsorbs any Juices which may be extruded due to the pulverizing .so thata pulp or mash of a semi-plastic and gelatinous material is provided.The' rotor of to sweep across the. upper surface of the trough and carryalong the trough in the direction of arrow 88 the mash which isdeposited diagonally of the trough.

This trough has a suitable side wall 81 so as to prevent the groundstockatthe free ends of the arms 85 from sliding oil the'same. An opening 88is provided in the trough at the end thereof' with a diagonal edge 89 sothat as the stock is pushed along by the arms 85, it will be pushed overthis edge 89 and dropped through the opening 88. Below this openingthere is a travelling belt 98 running at right angles to the directionof the trough and, as the opening 89 is diagonal of the trough and alsodiagonal of this belt 98, the stock so pushed over, the edge 89 will bedeposited evenly widthwise of the belt 98, although diagonally thereof.

Above this belt 98 ,there are supported a pinrality of curved fins 9|,92, 93, 94, 95 and 98 suspended from the support bar 91 above the beltwhich is a part of the framework of the machine, it being understoodthat suitable framework for supporting the moving parts in their desiredrelation is provided. The ends of each of these fins are progressivelyarranged at difierent distances widthwise of the belt 98 so thatthe-stock 4 is progressively deflected along the curved fin which is atsuch a curvature as to cause the belt to give the stock some forwardmovement which will assist in its deflection along the fin fordischarging the same over the edge 98 of the belt. In this manner, thestock is divided into a plurality of different divisions and isevenlydistributed onto the inclined apron 99 over which the stock slides intothe shaker I88. I

This shaker is made up of side walls and end walls with a screen in,undulating form "I for its bottom wall, as shown in Fig. 9. The inclinedthis pulverizer is driven from the motor 39 and belt 48', while the wormis driven from a motor 4| through belt 42.

The hopper 38 in turn discharges into a scroll chute 58 into which abucket belt 5| consisting of a plurality of buckets 52 flexiblyconnected by a belt 53 and trained over pulleys 54 and 55 exextendingtherefrom which rock a lever 88 pivoted as at 89 to.impart through linkI8 a vibratory action on the chute 88 pivoted as at 88, the same beingmoved in one direction by spring I2 .and in the other direction by themechanical impulses just explained) By this arrangement the chutecontinues to shake so that the sticky stock will not adhere to the samebut will continue to be discharged into the scroll chutelto be picked upby the buckets and maintain. a more even flow of the food material tothe dehydrator.

The pulverized food stock is discharged against a deflector plate 88(see Fig. 8) which is at such an angle by reason of its walls 8| and 82that it causes the pulverized semi-plastic mash to be depositeddiagonally of a trough 83. A sprocket chain 84 has one of its lengthsJust above the trough with arms 85 fastened to the chain so as wallportions I82. and a short bottom portion I88 provide a form havingreticulated sides to advan/ tageously discharge pulp when ibrated: Belowthis shaker there is asimilar s aker having an undulating screen I8 Iwith similar side walls I82 and bottom wall I88. and also a bottomscreen of a little larger mesh in a single plane designated I88. Theundulations of the screen I8I are greater than the undulations of screenI8I, while the screen I88 is ina single plane.

The' framework I8I of the apparatus pivotally supports links I88 whichare connected to the shakers I88 and I84 at I89and II8'which serve tosupport the shakers. Means for oscillating these shakers lengthwise isprovided, the arrangement being such that when one shaker moves in onedirection, the other shaker will move in the other direction, eachassisting to evenlyand lightly deposit the pulp in a layer onto atravelling belt in the form of a screen designated generally II I.

The drive for the conveying apparatus may be taken from shaft I8 whichis driven through the conveyor 8|, through bevel gears III, III, shaftII4 which through sprocket 8, chain III drives sprocket gear I n, shaftin to'drive the chain :1.

The drive for the belt 98 is' also taken from shaft I8 throughsprocket", sprocket chain II, sprocket gear I8 to gears I4, I8 on shaftII9 upon which the roll I28 is mounted and about which the belt 98 istrained. The vibratory movement of shakers I88 and I84 is throughlink'III, crank I22 on shaft I28 driven by pulley I24 from belt I28engaging pulley I28 on shaft I2'I driven bymotorI28. A p 1 Thetravelling belt III P ojects beyond the dehydrator which may bedesignated generally I35 and is seen in elevation in Fig. 3. This beltIII is of some known non-oxidizing material such as stainless steel withwhich the stock may contact without danger of destroying any of its de-'along its travel by suitable anti-friction means,

passing over pulley I36 at the head end and pulley I31 at the other endwhere a drive to belt I38 over pulley I39 from motor I40 is provided.

This dehydrator consists of a plurality of separate sections each ofwhich is a similar separate chamber, there being four shown. The firstsection differs from the other three, which are substantially alike, inseveral details which will be pointed out. Each section has a housing(see Fig. consisting of a top wall I and side walls I42 spaced from thebottom or floor and built about the conveyor belt III.

Within this housing there is supported a bank I43 and a bank I44 ofheating pipes. The bank I43 is above the conveyor belt, while the bankI44 is below. Steam is passed through these pipes and each bank isarranged in two sections so that there will be an inlet atone end and adischarge at the other end in alternate arrangement. The alternatearrangement enables an even distribution of heat to be provided. Thisarrangement is shown in Fig. 6 in which one section is designated I45having headers at I46 and I41,there being an inlet I 48 to the headerI46 and a discharge I49 from the header I41. The other section also hasheaders I46 and"'I41, but in this case, the inlet at I50 will be to theheader I41. andthe discharge I5I will be from the header I46. There is acommon discharge I 52 to a condensing trap I53 which may be controlledas at I54 and I55 that the amount of heat provided in the sections maybe under control. A valve controlling the inlet will of course beprovided for each individual bank. In the first section the two heatingbanks indicated at I43 and I44 will be provided, while in the second andsuccessive sections there will be particles of ground orfinely-pulverized pulp so that a space will be provided abouttheseparticles to assist in the circulation of air passing therethroughin each of the succeeding sections. A fan I58 is alsofprovided above theconveyor belt which is directed to cause air to pass lengthwise of thebelt, usually in the opposite direction to the travel of the belt, so asto afford an aspi-,

rator action drawing up the air through the belt from below. Baiiles I59are locatedat spaced points along the section which may be adjusted tocause the deflection of the air so driven parallel to, the beltdownwardly successively as dey I66 controlled by damper I61 delivers airthrough opening I65 into the conduit I83 across the top of the housing,then down each side of this housing and beneath the walls I42 at eitherside thereof and then upwardly through the banksof the heating coils anda conveyorbelt where it may be discharged through the conduits Icommunicating-with the housing through opening "I, there being anexhaust fan I12 in each of these discharge conduits to asssist in thedischarge of air therefrom. In the particular structure just describedthe fresh air enters and flows through the conduit I66 and passesthrough the opening I65 which is centrally located with respect to thedehydrator chamber, and then divides and passes down in the space oneither side of the inner drying chamber and absorbs heat radiated inthese spaces by the walls I42 oi',the

inner chamber and is preheated thereby prior to passing beneath thelower edgeof the walls I42. into the lower half of the dry chamber. Thisincoming air is further distributed by the flaring walls provided oneach side 01' the dehydrator which will cause a uniform flow of incomingair to pass beneath the lower edges of the wall lfl. In this arrangementI am able to control the volume of air admitted to each section so as toassure a uniform flow of fresh airover each section of the food beingdried. This arrangement also permits the proper control of ,dry bulbtemperature of the lower half of the chamberwhich will aifect the'wetbulb temperature of the food product being dehydrated, and consequentlyI am able to maintain the wet bulb at a temperature as low aspracticable to preserve the vitamin content of the food and maintain alarge uniform volume of fresh air constantly flowing through thechambers, and quickly exhaust the air before the same becomes saturated.

The first section or the dehydrator will be maintained at, for example,120 F. which will be warmer than the succeeding sections which may be115 F., as more moisture will be present-inthe pulp in this firstsection the wet bulb temperature of the stock or work due to evaporationwill be lower than the surrounding heated airwhich will be supplied, andthus to speed drying heated airabove that at which the stock may behandled without loss of value may be had. Since moisture passes from thepulp, the temperature will be reduced so that at no time will the pulpitself, or dried food, reach a temperature where injury to its vitamincontent may occur: In the case of carrots, the drying will be at between-115 degrees F., and the travel of the belt will be such that the'dryingoperation will be performed in a period of from 25 to '70 minutes. Themain unit for the steam which is utilized in the banks for heating isdesignated'l00'with the control at I8I. Individual controls for each of1 the sections are provided at I82, I83, I04 and I".

Indications of conditions within the dehydrator may be provided for eachsection whereby the The air which is taken in is ,Fconveyed'about thetop wall I4I or side walls I42 in conduits formed by a housing about thetop and side walls I,4I and I42 extending to the floor or bottom wallI6I which are conveniently, arranged by the provision of an outerwallI62 which taper to communicatewith a duct I63 extending across the topof the wall HI and with the space I64 between the walls I42 and I62. Thesupply conduit bailie plates space control may be known and if desiredautomati belt, means below said belt for directing air upwardly throughsaid belt and means above the belt directing air towards said baiiles tocause the air to travel generally parallel to the plane of the belt toprovide an aspirator action for the upwardly-directed air. v

2. In an apparatus for treating a food product comprising a plurality ofcompartments each having air inlets and outlets open to the atmosphere,means for individually heating and controlling the heat in eachcompartment, a conveyor belt passing successively through said pluralityof compartments, means for directing the air from the inlet to cause theair to travel to, the lower portion of each compartment and means tocause the air in the lower portion of each compartment to travelupwardly through the conveyor belt and additional means to cause the airto travel over the upper surface of' the belt in a directiongenerallyparallel thereto.

- 3. An apparatus for treating a food product comprising a plurality ofcompartments each having air inlets and outlets opening into theatmosphere, a conduit leading from said air inlets to the lower portionof said compartments, a reticulated conveyor belt passing successivelypositioned abovesaid belt at one 'end of said chamber, means forseparately controlling said heating elements, means at the ends of thesaid heating elements positioned beneath said belt for directing airupwardly across the surface thereof and through said belt and meanspositioned at one end of the upper positioned heating elements fordirecting air across the surface thereof and over the food product in adirection generally parallel to the plane of the belt and bailles in the"upper portion of said chamber and adjacent to the air outlets andpositioned at an angle with respect to a horizontal plane to aid indirecting the circulation of air over the food product.

6. An apparatus for treating, a food product comprising an elongatedchamber free of physical partition and provided with an entrance at oneend thereof and in which chamber a plurality of heating elements areprovided and distributed therein in such manner and individually'controlled to provide a plurality of progressively cooler compartments,with the warmer compartment adjacent to the said entrance, 9.reticulated endless conveyor belt extending through said through saidcompartments, separate heating elements positioned above and beneathsaid belt, and means directing air upwardly across the lower positionedheating elements andthrough said belt, and means directing air acrosssaid upper positioned heating elements and over the I food product to beacted on and baifles positioned at a location above said heatingelements to aid in directing the circulation of air over said foodproduct in a direction generally parallel to the plane of the belt.

4. An apparatus for treating a food product comprising a plurality ofcompartments each having air inlets and outlets opening into theatmosphere, aconduit leading from said air inlets to the lower portionof said compartments, 9. reticulated conveyor "belt passing successivelythrough said compartments, one of said compartments having separateheating elements positioned above and beneath said belt and meanspositioned at each end of the said lower positioned heating elements fordirecting air upbottom thereoi providing an air inlet thereto and havinga plurality of air outlets opening into the upper portion thereof, anendless reticulated conveyor belt extending from one end of said chamberto the other, ior conveying food products to be treated through saidchamber, banks of heating elements spaced from each otherand positionedbeneath said belt, heating elements chamber for successively carryingfood products to be acted on through said compartments, means a todirect air by said heating elements overand about said food product, anda plurality of spaced air outlets located in the upper portion of eachcompartment for exhausting air therefrom for substantially preventingair from one compartment to flow through the other.

7. A dehydrator apparatuscomprising an elongated chamber provided withan entrance at one end thereof and in which chamber a plurality ofheating elements are provided and distributed therein in such manner andindividually controlled to provide a plurality of progressively coolercompartments, with the warmer compartment adjacent to the said entrance,a reticulated endless conveyor belt extending through said chamber forsuccessively carrying theproducts to be acted on through saidcompartments, means to direct air by said heating elements over andviding air inlets thereto, means in said chamberabove said product, andan air outlet in each compartment for exhausting air therefrom forsubstantially preventing air from one compartment to flow through theother.

8. A dehydrator apparatus comprising a chamber open at the bottom oneither side thereof profor heating the same, an air conduit extendingabout said chamber the walls of which include the top and side walls ofsaid chamber, said conduit having an air .inlet therein opening in eoneither side of said chamber converging towards the air inlet in saidconduit for distributing the air flowing therein substantially equallyalongthe bottomof said chamber.

.2 HENRY 'J. BURnE'rr.

